Carburetor



Sept. 5, 1944. H. F. LEE

CARBURETOR Filed June so, 194s 2 Sheets-Sheet 1 H. F.Y LEE CARBURETOR Sept. 5, 1944.

Filed June 30, 1945 2 Sheets-Sheet 2 lwvwvbo'v HARRY F. LEE.

Patented Sept. 5, 1944 CARBURETOR Y Harry F. Lee, Gallup, N. Mex.

Reled for abandoned yapplication Serial No.

237,981, October 31, 1938.

This application l June 30, 1943, Serial No. 492,827

(Granted under `the act of March 3, 1883, as amended April 30, 1928; 370 0. Gr. 757) 2 Claims.

This application is made under the act of March 3, 1883, as amended by the act of April 30, 1928, and the invention herein described, if patented, may be manufactured and used by or-for the Government of the United States of `America for governmental purposes without the payment to me of any royalty thereon. Y

This application is a-rele of Serial No. 237,981, `liled October 31, 1938.

. This invention relates generally to carburetors and it is more particularly concerned with car-y buretors of the down-draft typevfor usel on internal combustion engines.

The general object of this invention isthe provision in a carburetor of the type mentioned of an improved valve arrangement in conjunction with the mixing chamber which will operate automatically to admit more or less air from the air inlet to the mixingbhamber in accordance with engine requirements. 1

The following description, togethervwith the accompanying drawings, will fully disclose this invention, its construction and operation of parts, and further objects and advantages thereof will be apparent. Y Y

In the drawings:

Figure l is a cross-sectional View in elevation of an embodiment of my invention. Y f

Figure 2 is a plan section view of the device along the line 2-2 of Figure 1. l I

Referring with more particularity to the drawings, in which like numerals designate like parts, the carburetor body comprises an upper cast tubular member 4, a middle cast tubular member 5, and a lower cast tubular member Ii, the members when assembled forming a continuous, upright, tubular air passage.` The upper member 4 carries within it the yieldable air Valve regulating assembly and provides the only air inlet to the carburetor. The upper member 4 is'attached to the middle member 5 and held in alignment therewith by means of a horizontal flange 'I. To theV upper portion 8 of the member 4, the usual air cleaner 9 (fragmentarily shown) is attached to the device. Integral with the member 4 is a cup-shaped member I0, concentrically secured to the inner walls by means of ribs II.

The upper rim of the cup is recessed to provide Va removable mounting for a shield I3. Integral .with said cup-shaped member I is an elongated vertical collar I2, slidably engaged with a shaft I4. A sleeve I5 is slidably disposed around the -collar I2, and has a anged portion Ia upon which the lower ends of two concentric springs :I6 and I'I are seated.v The upper end of the outer or idling spring I'I is adjustably secured to the threaded top ofthe shaft I4, by means ofthe nuts I8 and I9. The upper end of the inner or high speed spring lterminates at a point below the top of spring I'I, where it is slidably engaged with the shaft I4. Between this upper terminalpoint of the spring I6 and the vupper terminal point of the spring I'I, nuts 2U and 2I are adjustably disposed on the shaft I4, and are adapted to abut the end ofthe spring I6 when the shaft I4 is translated a predetermined distance downward. Y l

` .The middle tubular member 'carriesy an inwardly extending flange having an. annular downwardly facing shoulder 22, 'constituting the outer seat for the air valve. Av Venturi tube 23 isfcoaxially disposed concentric within the middle member 5, supported by means of radially extending ribs 24 connecting it to the middle member. Said Venturi tube is outwardly flanged at .its upper end to form an annular downwardly facing shoulder 25, constituting the inner seat for the vair valve 26, which is in the form of a wide washer and is coaxially disposed around said Venturi tube 23 below the shoulders 22 and 25. rIn the closed position, the valve 26 contacts the shoulders 22 and 25 and seals the air-passage opening therebetween. The valve 26 is'supported by a spider 2l having arms 27a extending downwardly between the ribs 24 andattached to the air valve allowing space for passage of air between the ribs and arms. The spider 2l is secured to the lower end of the shaft I4, and by the action of the spring I'I, the valve 26 is normally yieldably held against the seats 22 and 25 by means of the yieldable air valveregulating assembly.

The tubular member 5 is hermetically sealed Y between the upper and lower'tubular members 4 and 6 by means of gaskets 28 and 29, cap screws` 30 and lock washers 3|. The tubular'member 6 is tapered toward the bottom; the innerY walls being in the form of another Venturi tube conforming to the general shapeV of an inverted milk bottle neck, the larger upper section 32 constituting a part of thesuction chamber, and the lower section 33 constituting the throat or mixing chamber. YThe members 4, 5 and 6 thus form 23, and is supported by a suitable streamlined bracket 34 having a channel 35 through which fuel is delivered from the outside. Said jet 36 comprises a tubular member of two sections 40 and 4I having enlarged portions with annular openings 31 and 38 forming the primary and secondary nozzles through which fuel is discharged. A semi-spherical deflection head 39, with a. screwdriver slot thereon, forms the upper end of section 40 which screws into an internally threaded seat below an enlarged mouth of section 4I, thereby forming the opening 38.' Immediately above the jet 36, a Venturi tube butteriiy valve 42 for adjustably controlling the flow of air through the Venturi tube is disposed within the Venturi tube 23 on a horizontal shaft 43 rotatably mounted through the walls of the Venturi tube 23 and the middle member 5.

Beneath the bracket 34, throttle butterfly valve 44 is disposed on a shaft 45, which shaft is rotatably mounted in bearings 46 and 41 in the walls of the lower member 6 parallel to the shaft 43, one end of said shaft 45 extending through said wall on the same side as the shaft 43.

An arm 48 is secured to the exterior end of the shaft 45 and an arm 49 is secured to the exterior end of the shaft 43, substantially as shown.

Another shaft 50 is rotatably mounted through the upper member 4 to which is attached a cam 5I beneath the flange I5a. The exterior end of the shaft 50 carries forked arms 52 and 53. The lower arm 53 is pivotally attached to a link 54. The other end of this link is bifurcated to straddle the arm 49, and is provided with slots 55, 55, which slidably engage a pin 56v extending through the end of the arm 49. A spring 51 is mounted under tension between the end of the arm 49 and a convenient xed point 58 of the member 6 by means of which the butterfly valve 42 is normally held in an open position. This valve is restrained from closing under the action of the spring 51 by means of an abutment (not shown) normally engaging the under side of the arm 49.

The operation of this invention is as follows: Air drawn through the air cleaner 9 enters the carburetor through the upper tubular member 4 as the inlet. At low idling speeds the force of air owing from the air inlet is insuflcient to open the air valve 26 more than the adjusted amount against the action ofthe idling spring I1. With said air valve nearly closed most of the air is forced through the Venturi tube 23. The flow area being considerably reduced through this Venturi tube, the velocity of the air is correspondingly increased toward the throat of the tube where it acts upon the fuel jet nozzles, thereby inducing a flow of fuel into the air stream which is expanded and turbulently thrown into the lower section 33 where a mixture of the gas and air is accomplished. This mixture then passes around the butterfly Valve 44 into the manifold of the engine.

When the butterfly valve 44 is opened wider than for low idling speeds,'an increase in the flow of air is accomplished creating a greater pressure on the air valve 26, which valve opens against the action of the force-adjusted spring I1 to a degree proportionate to the increase in pressure'on the valve. By this means, the air passing through the air valve 26 with a given velocity, intersects the stream of atomized fuel and air, issuing from the bottom of the Venturi tube 23 at a greater velocity, thereby inducing turbulence between the two air currents, and resulting .in an almost per- 75 feet mixture which passes through the lower section into the manifold of the engine.

The design and location of the jet nozzles will not cause an excess flow of gas at the lower engine speeds. The common practice in many other carburetors is to regulate the flow of gasoline only, throughout the range of the carburetor, except at idling speeds, but in this invention the operation is performed entirely by regulating the flow of air into the carburetor.

Although the Venturi tube 23 cannot supply most ofthe air for full throttle operation, it does supply air at a higher velocity than the air valve, thus giving the Venturi tube 23 a chance to deliver a thoroughly atomized fuel to the mixing chamber. Air flowing through the Venturi tube 23 is accelerated the instant the throttle is opened causing a rich mixture to start flowing if the throttle is opened suddenly, but as the air valve works automatically it will admit the correct amount of air at almost the same instant. This action makes the use of an acceleration pump unnecessary and results in a simple fool-proof carburetor.

The air entering the carburetor rushes through the Venturi tube 23 at great speed even when the throttle is part way open, due to'streamline design and small diameter. Also, on account of the automatic action of the air valve 26 in which it opens only as more air is needed in the mixing chamber, the correct proportion of air to the atomized gasoline and air mixture, as it comes from the discharge end of the Venturi tube 23, is maintained.

The points of fuel discharge for both of the fuel jet nozzles are shaped to deliver the fuel in a very thin circular spray to the Venturi tube and in this way they give a more thorough atomized fuel to the engine.

The correct air and fuel mixture is determined in part by the inside diameter of the Venturi tube and the size of the jet openings used and also by the diameter of the suction chamber immediately below the outer air valve seat. Final adjustments can be obtained by either releasing or applying tension on the air valve spring I1 as may be needed. The springs I6 and I1 are very sensitive to adjustments and if the mixture is too rich or too poor, tension may be increased or decreased slightly by means `of the adjusting nuts I8 and I9, and 20 and 2I. The air valve is not affected by adjustments of the nuts 20 and 2I except under high speed or motor loads with open throttle.

The cam 5I, attached to the shaft 5U, is operated or manually controlled from the instrument panel by means of a choke wire or rod (not shown) connected in `some suitable fashion to the upper arm 52. The purpose of this cam is to put increased tension on the springs I6 and I1 by raising the flange I5a. This Vaction is provided so that the air may be. partially or completely stopped from enteringthe carburetor through the air Valve when a rich starting mix-l ture is desired. The cam .can be rotated about The butterfly Valve 4.2 is, controlled and operated by the connecting link 54 depending from the lower arm 53. By. means of the slotted lost motion connectionofthe link 54 to the. arm 49, the cam 5I may be initially rotated about 45 before .the normal position Aof .the Venturi valve 42 is effected, -the. final rotation of the cam effecting .a closing of the valve. Consequently, the .shaft ,50 rmust be rotated about 90 before the air is shut oil' completely, to complete a so-called choking operation.

Having thus described my invention, I claim:

1. In a'down-draft type carburetor, a carburetor body having a continuous, upright, tubular air passage, the lower portion thereof forming a mixing chamber and the upper end an air inlet, a Venturi tube mounted within an intermediate portion of the air passage by means of radially extending ribs attaching the upper end of the Venturi tube to the carburetor body, the lower end of the Venturi tube terminating in the mixing chamber, a fuel discharge jet disposed in the lower end of the Venturi tube, a Venturi tube valve for adjustably controlling the air owing from the inlet through the Venturi tube, -said valve being disposed within the Venturi tube above the fuel discharge jet, an air passage opening concentrically disposed around the Venturi tube, an annular air valve located below the radially extending ribs and opening downwardly toward the mixing chamber for controlling the Y 2. The subject-matter of claim 1, in which the carburetor body comprises three separate tubular members secured together, the lower tubular member forming the mixing chamber, the middle tubular member supporting the Venturi tube, and the upper tubular member forming the air inlet and supporting the yieldable means therein.

HARRY F. LEE. 

